Fedora may receive backing from RH, but it’s still community-ran. Similar to how Linux itself is backed by the likes of Google/Meta/Huawei/etc but is isn’t ran by them.
And they didn’t close-source RHEL. I don’t like the license changes they made either, but calling it closed source is inaccurate.
If you’re a customer of theirs, you can see the source code. The license customers agree to is certainly a restriction, but it’s not all of a sudden closed/proprietary software.
And finally, despite that recent move, RH remains probably the biggest contributor to desktop Linux. If you want to avoid their work… good luck. It’s literally everywhere.